Ok. I was on a hot day hard mountain drive the other when my 240 started sputtering badly and died. I pulled over and sat a bit and restarted. I noticed some unusually loud noise from the fuel pump but had to get on. I got going just barely when it happened again. I pulled over again and sat in some shade for about 45 min. Then I restarted and pulled off the highway. I drove for about 25 min. on a side street with no problems and deemed the car safe and got back on the highway again. I drove the remaining 150 miles home without incident.

From my reading here on the BB, I think it's vapor lock. And after thinking about the usual suspects (pre-pump, main pump, relays etc.), I think it's the fuel pump check valve. I read that it's main function is preventing hot weather vapor lock. Is this true? My car also seems to lose residual pressure when I turn off the car. That's a symptom of a bad check valve too is it not?

Many thanks as always.